Industrial oven



May 18, 1954 C. F. MAYER INDUSTRIAL OVEN 4 Sheets-Sheet 1 Filed July 8,1952 .4 rra Awa ys May 18, 1954 c. F. MAYER INDUSTRIAL OVEN m 4Sheets-Shet 2 Filed July a. 1952 v-j uvm/Ton.

614m EMA ya@ 5ML O1/lm rra RNE V5 May 18, 1954 c. F. MAYER INDUSTRIALovEN 4 Sheets-Sheet 3 Filed July 8, 1952 M T m w.

61ML F.' MAYM Aly Arran/vaya May 18, 1954 Filed July 8, 1952 C. F. MAYERINDUSTRIAL OVEN 4 Sheets-Sheet 4 INVENTo OWL FMA YER BY dmfcmwArron/ways Patented May 1S, 1954 7 Claims.

This invention relates to industrial ovens, particularly of the classused in foundries and similar plants for drying freshly made cores andthe green sand linings of ingot and other large and heavy mold flasks.

In ovens of the class referred to the work is supported upon portableracks or cars and, with the oven closed, heated gas (using the term inits broad sense to embrace air) is continually forced into the oven, andat least a major part of said gas is simultaneously withdrawn` reheatedand recirculated, any remaining part being exhausted to the atmosphereand replaced by fresh air that is drawn into the system at one place oranother, as about the heater as combustion air, and possibly elsewhere,as will be readily understood.

Hereto-fore the supply ducts, from which the heated gas is dischargeddirectly into the oven, have been located along the side walls near thefloor, and the so-called recirculating ducts and exhaust ducts have beensituated within the oven adjacent the top thereof. This arrangement wasdoubtless dictated by the well known principle that warm air rises, andthe obvious fact that such action is accelerated by the natural stackdraft to which the exhaust ducts are subjected, sometimes augmented bythe suction of an eX- haust fan or blower.

While such a circulating system has generally been regarded assatisfactory, its eiciency and reliability have been greatly impaired inmany instances by damage to the supply ducts resulting from the saidducts being struck and deformed by p-arts of the work work has beenimproperly placed upon the cars, project too far beyond the sides of theconveyances. Lack of care in arranging the work on the cars and roughhandling of the equipment, both of which contribute to the difficulty,are more or less prevalent in foundries, where the work that is beinghandled is usually very heavy and cumbersome.

The two principal objects of my invention are to improve thecirculation, and the distribution and diiusion, of the hot gas throughthe oven thereby to .increase the efciency of the latter; and to arrangethe ducts so that none is within reach of any part of the work withwhich the portable rac-ks or cars are loaded.

In the attainment of these objects I arrange the supply ducts, and theexhaust ducts, ii' any, at the top of the oven, and the recirculatingducts, each preferably in the form of a trench, below the floor level oithe oven.

doors, through the that, because the irri) A further and importantadvantage resulting from such a duct arrangement is the availability ofsubstantially the full width of the oven space for work accommodation.To this end, the width of the door opening is made to correspondsubstantially to the internal transverse dimension of the oven.Accordingly, it will be seen that my invention provides maximum capacityrelative to the external width of the oven.

I have said that the recirculating duct or ducts of my improved oven arebelovT each des-irably in the form of a trench. It is a further objectof my invention to house in such trench or trenches the car pullingmeans, which may take the conventional form of a pull-cable, or anendless chain.

While my invention is not particularly limited to ovens of the so-calledcar type, nor to ovens that are open at both ends, .l have chosen to soillustrate it herein; and although a lift door is preferable for closingan open end of the oven as herein shown, other kinds of doors may beemployed.

rihe above enumerated objects and advantages, with others that willappear as this description proceeds, are attained in the embodiment ofthe invention illustrated in the accompanying drawings wherein likeparts are designated by like reference numerals throughout the severalviews.

In the drawings,

Fig. l is a front elevational view oi an industrial oven constructed inaccordance with the invention;

Fig. 2 is a plan view of the oven;

Fig. 3 is a sectional side elevation of the oven, the plane ci sectionbeing indicated by the line 3-3 of each of Figs. l, 2 and 4, the Viewbeing shortened to avoid further reduction of the scale to which it isdrawn by breaking away the ends and insetting them beneath the majorportion of the view;

Fig. 4 is a transverse section through the oven on the line flof each ofFigs. 2 and 3, this view being drawn to a somewhat larger scale than theothers.

The oven comprises a casingj designated generally by the referencenumeral I, including a tcp wall 2 and side walls 3, the latter beingshown as mounted upon curbs 5 that are integral with and rise from afloor 6 of suitable material, such as concrete. The walls 2 and 3 areillustrated in a conventional manner as being oi insulating material,and in practice they may be composed of panels of appropriate size thatconsist of sheet metal shells illed with suitable insulation the floorlevel,

u and held together by a structural iron fra-mework, all of which iswell known to those familiar with this class of ovens, and, furthermore,has nothing to do with the invention at hand.

The casing I is shown as open at each end, entirely from one side wallto the other, and from the :door upwardly to a shallow drop wall orlintel 8. Thus, in the present form of the invention, the oven isprovided with an entrance at one end and an exit at the other. GuidesIO, which may be in the form of outwardly opening angles, rise from thefloor on opposite sides of each end of the oven casing immediatelyadjacent thereto,

and arranged with its lateral edges within-fthe p posed guides It ateach end of the oven casing is a door that is slightly greater in heightthanthe opening with which it is associated. that is located at what maybe regarded,` for the present purpose, as the entrance to t e'ovenfis..

designated I2, and the one located at the exit is designated I3. Thedoor I2 .is insulated and-may beof the .same general .construction asthe wall panels .above described. A .beam I-I extends between and issuitably connected tothe upper ends of the guides I0 of each pair, andmounted thereon are pillow blocks. or bearings I 5.wherein is journaledashaft I6. It will be observed that the pillow .blocks or` bearings arearranged in pairs, and between those of each .pair is a sprocket I7 thatis suitably securedagainst rotation to-the shaftV I6. A chainIB isengaged over each of the sprockets Il' and hasA one of itsends connectedat i9 to the topf thedoor .I2 or..I3 and its other end anchored at toVthebeam. Hl. Riding within a depending loop of each chain, between theanchored `end thereof and. the corresponding sprocket I7, isa rotaryguide. orspr cket 2I that has suitable connection with a counterweight22. Said weight is shown as a bar that iscommonto allV of the chainslocated at the corresponding end of the oven. One end of the shaft ishasdriving connection, through suitable reduction gearing enclosed in acasing 25, with an electric motor 2l, said casing and motor beingsupported on a shelf 28 that extends laterally ,from the adjacent guideIIJ... Through the customary circuits and remote beioperated in.reversedirectionsA to raise andV lower the correspondingdoor.

Located within the oven casing. adjacent the top wall 2 are supply ductsBilanci 3 I., shown as of thesamecross sectional size Vand. shape, and.a4

somewhat narrower `supply duct 32. The ducts 30 and 3l are preferablytted withinthe top corners of the casing and extendfrom one endof theoven tonear the Aopposite end thereof. TheV duct 32 is of the samelength as the ducts 30 and..

3l, and is desirably located substantially midway betweenrthe two. Theduct 32 has outlet. openings 33 in its side walls, and similaropeningsSA in its bottom wall, while the ducts lland 3l haveoutletopenings 35 in their inner vertical walls and relatively wide outletopenings '36 intheir bottom walls. In accordance with common practice,the outlet openingsv of the supply ducts are equipped with damper platesso that the quantity' The door the iioor alongside the oven casing,incidentally in axial alignment with a heater 42 of conventional typecommonly used in connection with recirculating systems of industrialovens. The

eater may be of the oil or gas fired variety to which ambient air isadmitted for combustion purposes. The outlet of the heater communicateswith the inlet of the impeller or blower 4I through a conduit 134. Inorder to conserve heat, the conduits 4f] and 44 and the casings of theimpeller or blower il and heater 42 may be encased in insulatingmaterial, as indicated. An electric motor d5 is shown as having drivingconnection, through abelt 45, with the shaft 4'! of the impeller orblower 4I.

An exhaust duct 50, provided with inlet openingsv 5I, is .supportedwithin and transversely of the oven casing in the horizontal plane ofthe previously described supply ducts and adjacent the entrance end ofthe oven. Obviously, the supply ducts may be made shorter, so .thatanother .-exhaust duct maybe located at the exit endof'the casing, ifdesired. An exhaustifan or blower .53 is shown as mountedon top of theoven casing. and the inlet thereof is placed in communication with theexhaust duct through a conduit 54 that extends through an opening in thetop wall ofthe oven casing.. The outlet of thefan or blower .53r

opens into an exhaust stack 55. An electric motor.

56 has driving connection, through avbelt 51,'witl1 the. shaft 5B ofthefan or blower 53.

Situated below the level of the floor 6, which desirably consists of asolid monolithic structure, and .opening through the `floor .into theinterior of the oven casing, are relatively narrow elongated depressionsor formations providingl trenches 60 that constitute recirculatingducts. Although I have shown two such trenches, one of .a somewhatlarger capacity may be employed, in which. case it would vpreferably belocated at about the. longitudinal center of the casing. This alternas.

tive arrangement is so obvious that specic illustration thereof isdeemedunnecessary. The two trenches communicate with each other througha cross duct 62, and with the heater 42 through a subterranean conduit63. The top of the cross duct 62 may be closed by extending the floor 6thereover, or said cross duct may be open at the top. as are thetrenches 6D. if additional capacity4 of the gas recirculating facilitiesis desired.

The trenches 6D extend substantially the full.

length of the oven casing, and each is shownas disposed centrally of atrack composed of parallel The tracks.

rails G5 that are set into the iloor. may lead from the area of thefoundry or plant where the cores are made'and the moldsare lined, to theoven and 'in'through the entrance end of the casing, and thence, throughthe exit end, to points of delivery.

Cars 66, whereon the work, designated Wis. loaded, traverse the rails S5and, in the present instance, are propelled by car pulling meansAccording to prevailing practice,`

designated 6l'. the means 67 may consist of pull-cables or endlesschains, the latter being schematically illustrat-ed in the drawings.These chains are guided over sprockets or the like 69, housed in pits70,'

and are driven by suitable power means (not shown) that may be locatedin one of the pits. Beyond the endsof the oven, the car pulling means orchains operate in relatively narrow channels in the floor oftheiplant.These chan-- nels merge with the trenches which, by reason of 'theirlocation, provide especially appropriate accommodations .for the .carpulling means .sub-

stantially throughout the length of the oven. The upper and lowerreaches of the endless chains are supported and guided throughout thelength of the trenches by upwardly facing ohannel beams 12. These beamsare connected together in properly spaced relation to each other, andare shown as supported from the bottom of the trenches, by uprightmembers 13. Any selected number of plates 15 are adapted to be arrangedin variable spaced relation to each other along the top of each trenchinthe present embodiment on each side of the car pulling means 61, withtheir inner edges sustained by the structure composed of the channels 12and members 13, and their outer edges supported by the floor 6, withinrabbeted grooves thereof. The plates 15, by reason of the fact that theymay be varied in number and spacing, constitute regulable means forchanging the gas recovery capacity of the recirculating ducts ortrenches.

Any suitable expedient may be employed for separably connecting the carpulling means 61 to a car. Means for this purpose is more or lessschematically illustrated in the drawing as cornprising entering andreceiving members 16 and 11, one carried by the chain and the other by acar.

In the use of the oven, the work W, illustrated as stacks of large moldlasks, is arranged on the cars so as to be properly spaced from the sidewalls of the oven and provide free circulation of the hot gas throughand about the work. The cars are now moved into the oven by the carpulling means 61 and the doors l2 and i3 closed. With the gas heater 42in operation, current is turned into the driving motors 45 and 56 of theimpeller or blower 4l and the exhaust fan or blower 53, respectively.The hot gas from the heater will be drawn through the conduit M to thecasing of the impeller dl and delivered under pressure through the duct42 and cross ducts 38 to the supply ducts 3D, 3| and 32. For a betterunderstanding of a practical application of the invention, it may berelated that, in a typical installation, the heater is of six million B.t, u.

capacity, and, with the impeller M in operation, a static pressure offrom 4 to 6 prevails in the oven. In fact, it requires a static pressuresubstantially within these limits to force the hot gas downward inopposition to the natural tendency of such gas to rise. It is evidentfrom this that the hot gas within the oven is thoroughly diffused andeiectivelv distributed through and about the work and that theefficiency of the oven is accordingly very high. As previouslyexplained, the

outlet openings of the supply ducts may be effectively regulated by thedamper means associated with such openings in accordance with prevailingpractice, and by virtue of the regulable means provided by the plates 15for altering the recovery capacity of the recirculating ducts ortrenches S0, such approximate percentage of the oven atmosphere as maybe desired may be reheated and recirculated, the remaining percentagebeing carried off through the exhaust duct 5l! and stack 55. A practicalratio would be about '70% for reheating and recirculation and theremaining percentage for withdrawal, the latter being replaced byatmospheric air entering about the doors and through the heater 42 ascombustion air. Some leakage will occur elsewhere, as through thechannels wherein the car pulling means is housed exteriorly o the ovenand which communicate with the recirculating ducts or trenches 60, asabove explained.

At the conclusion of the drying period the doors are opened and the carsare withdrawn from the oven by the car pulling means, in the presentinstance through the exit end of the oven where the door i3 is located.

In addition to the high efficiency of the oven assured by my novelmethod of circulation and distribution of the hot gas, the ductarrangement affords maximum space for the accommodation of the work andeliminates all possibility of damage to the ducts from the cause aboveset forth; and although it is not entirely necessary, it is desirable tocontinually replace a part of the oven atmosphere with fresh air, asherein provided, in order that the recirculated gas be less contaminatedby the vapors given off by the work.

Having thus described my invention, what I claim is:

1. An industrial oven comprising an open end casing including a solidfloor, closure means for the open end of the casing supported formovement between open and closed positions, supply duct means situatedadjacent the top of the casing for delivering heated gas directlythereto, a trench formation in the floor constituting recirculating ductmeans disposed below the floor level and opening through said level intothe interior of the oven casing, gas heating means and gas impellingmeans communicatively connected together for the heating of the gas andfor the circulation of the same therethrough and having a gas inlet anda gas outlet, conduit means communicatively connecting said gas outletto said supply duct means, and further conduit means communicativelyconnecting the recirculating duct means to said gas inlet, whereby todraw gas from the oven casing through the recirculating duct means andmove it through the heating means and return it under pressure to theoven casing through said supply duct means, parallel rails supported bythe floor, one on each side of said trench formation, and extending outthrough the open end of the casing to provide a track on which cars maybe moved into and out of the oven, and car moving means operating withinsaid trench formation.

2. An industrial oven comprising an open end casing including a topwall, side walls and a solid monolithic floor, closure means for theopen end of the casing supported for movement between open and closedpositions, a plurality of intercommunicating supply ducts within theoven casing extending substantially the length thereof in closeproximity to the top wall, each duct having outlet openings at closelyspaced intervals throughout the length thereof for the discharge of gasinto the oven, a relatively narrow trench formation in the floorconstituting a recirculating duct situated below the floor level andextending substantially the length of the oven casing and opening intothe oven through said level, gas heating means and gas impelling meanscommunicatively connected together for the heating of the gas and forthe circulation of the same therethrough and having a gas inlet and agas outlet, conduit means communicatively connecting said gas outlet tothe supply ducts, and further conduit means communicatively connectingthe recirculating duct with said gas inlet, whereby to withdraw gas fromthe oven through the recirculating duct and move it through the heatingmeans and return it under pressure to the oven through said supplyducts.

3. An industrial oven comprising the combination and arrangement ofparts dened by claim aises-,s1 3:

2T andfin additionthereto, an' :exhaust Aduct extending'transverselyY ofwithin the planeof the theends `thereof and having openings throughwhich gas is admitted thereto from the oven, and suction means incommunication with the exhaust duct.

4.' AnA industrial oven comprising' the combination 'and arrangement ofparts delined by claim 1, and," in addition thereto, two series of looseplates adapted to beplaced across the top of the frecirculating ductinselected numberand spaced relation'to one another to regulate thegasrreceiving capacityl of the recirculating duct, andfmeans forsupporting the two series of plates in laterally spaced relation to eachother to ai-A ford :access therebetween to the car moving means.

5:'fAn industrial oven comprising an open end casing including a topkWall, side walls and a solid monolithic iioor, ciosnre means for theopen end of the-,casing supported for movement between open` andclosedpositions, supply ducts within theA oven casing extending substantiallythe lengththereof in close proximity to the top wall ofztlie casing andhaving outlet openings for the delivery of gas to the oven, a trackconsisting of parallel 'rails supported by and within the floorwiththeir top surfaces in substantially the plane thereollleading intothe oven through the open endof the casing, a relatively narrow trenchformation in the iioor constituting a recirculating duct below the oorlevel and situated substantially midway between the rails and extendingsubstantially the length of the oven casing and opening into the oventhrough the floor level, gas heating means and gas impelling meanscommunicatively connected together for the heating of A'the gas and forthe circulation of the same therethrough and having a gas inlet and agas outlet,conduit means communicatively connecting said gas outlet tothe supply ducts, and further conduit means eommunicatively connectingthe recirculating duct with said gas inlet, whereby tolwithdraw gas fromthe oven through the recirculating duct and move it through' the heatingmeans and `return it under pressure to the oven through said supplyducts.

6.v An industrial oven comprising the combinationand arrangement or"parts dened by claim 5,v wherein the recirculating duct providesaccommodations for means for moving cars into and out ofthe'oven alongthe said track and wherewith the oven. casing entirely supply ducts andbeyond connections, car moving means comprisingnaf separable fdrivlngalinear element, a guiding and supportingstruc-L- ture for said carmoving means situated'inthe recirculating duct substantially the sidesthereof, a plurality of midway between' loose plates, and' means forsupporting said plates at approxi'- mately iioor level in spacedrelation to each other? and between said guiding and ture and the flooradjacent the sides .of the re-' circulating duct, said plates beingchangeable iinl supporting 'struce number and spacing thereby toconstitute regue.

lable means by which the of the recirculating duct may be varied.

gas receiving capacity'.

7. An industrial oven comprising a casing int-A of the casing supportedfor movez-w intercommunicating supply ducts within'theoven:

casing extending substantially the length thereof 1n close proximity tothe casing and the third being between said two, each duct having outletopen'.`

top wall, two ofwsaid substantially midway ings for delivery of gas tothe oven, a trench, below the iioor level and extending substantially.

the length of the oven and through the floor,

opening into the oven gas heating means and'gas"` impelling meanscommunicatively connected to-z gether for the heating of the gas and forthe cir' culation of the same therethrough and havmg'a:

through the trench and move it throughthe heating means and lreturn itunder pressure to" the oven through said supply ducts.

Reerermesv Cited in the le of this patent UNITED STATES PATENTS

